Service brake systems degrade and fail. Vehicles with these degradations and failures must meet minimum performance requirements established by Original Equipment (OE) manufacturers and legal entities, such as the United States (US) Government and Commission of the European Communities (ECE). The US Federal Motor Vehicle Safety Standard (FMVSS) 135 outlines several minimum vehicle performance requirements, including the following as examples:                Cold Effectiveness (reduced effectiveness of brake linings),        Antilock Functional Failure (failed wheel pressure outlet valve or failed hydraulic pump in Anti-lock Brake System, ABS, hydraulic control unit),        Hydraulic Circuit Failure (primary, secondary or both),        Brake Power Unit or Brake Power Assist Unit Inoperative (low or no vacuum), and        Hot Performance (reduced effectiveness brake linings).        
The service brake system can be configured to provide adequate brake torque and meet minimum vehicle performance requirements. Examples include providing larger pedal ratio, higher friction linings, larger booster diameter, larger rotors, smaller master cylinder bore, etc. There are other brake torque support functions that increase brake torque to meet minimum vehicle performance requirements. Examples include an Electric Vacuum Pump (EVP) that increases brake booster vacuum and ABS/stability control pump. The above possible solutions may involve weight, packaging, durability, cost and other service brake performance and subjective brake feel characteristic compromises that are not desired.
Thus, there is a need to provide a system that provides brake torque in order to meet minimum performance requirements in the cases of degraded and failed service brakes that uses existing brake system components, does not increase weight, and does not compromise service brake performance and subjective brake feel characteristics